| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 6 |
0.6%
|
| -7 | Does not apply | 15 |
1.4%
|
| 0 | No obstacle | 301 |
27.7%
|
| 1 | Minor obstacle | 131 |
12.1%
|
| 2 | Moderate obstacle | 201 |
18.5%
|
| 3 | Major obstacle | 233 |
21.5%
|
| 4 | Very severe obstacle | 199 |
18.3%
|